We have found that treatment of male rats with narcotic drugs prior to mating causes a marked increase in the neonatal mortality of their progeny. We plan to further identify the conditions affecting and the mechanism(s) responsible for this effect and to search for sublethal effects on the growth, development, and behavior of such progeny. We will examine possible genetic effects, that is, effects passed on to the progeny of the offspring under study. The widespread abuse of narcotic agents and the employment of methadone as a tool in the rehabilitation of narcotic abusers define an acute need for the above studies. Our studies also have a broad implication as a possible basis for the cause of congenital anomalies by investigating effects on the male rather than the usual concern with drugs given to women during pregnancy. BIBLIOGRAPHIC REFERENCE: Smith, Durwood J. and Joffe, Justin M. Increased neonatal mortality in offspring of male rats treated with methadone or morphine before mating. Nature 253: 202-203, January 17, 1975.